Chapter 6: Sensation and Perception
How do we detect loudness?
the number of activated hair cells -if a hair cell loses sensitivity to soft sounds, it may still react to loud sounds
figure-ground
the organization of visual field into objects (the figures) that stand out from background/surroundings (ground) ex. recognizing a voice from a crowd of noise
sublimal
stimuli you cannot detect 50 percent of the time; below absolute threshold
interoception
stimulus from inside body -sensory reception on internal organs
gestalt
"form" or "whole" -when given a cluster of sensations, people organize them into a whole, integrating pieces of information into meaningful wholes -filter information and construct perceptions -in-life: logos (Mac, twitter ex, panda)
What theories help us understand pitch perception?
-Hermann von Helmholtz's place theory -Frequency theory -volley principle
Describe the process that transforms vibrating air into nerve impulses, which the brain decodes as sounds
-Sound waves enter outer air, which channels waves to the eardrum, causing it to vibrate -in the middle ear, a piston made of 3 bones (hammer, anvil, and stirrup), transmits the vibrations to the cochlea, a tube in the inner air -the incoming vibrations cause the cochlea's membrane to vibrate, jostling the fluid that fills the tube, bending the hair cells lining the basilar membrane -movement triggers impulses in adjacent nerve cells, which converge to form the auditory nerve, which sends neural messages to the auditory cortex
Describe sound waves
-amplitude: determines loudness -frequency (length): determines pitch (long waves have low frequency, low pitch, short waves have high frequency, high pitch)
anchoring
-base impressions of objects on surroundings -asked people to guess certain factoids -asked participants to high or low anchor condition, asked to provide own guess: what anchor was influenced responses--perceptions of world depend on context we're given -ex: sales discounts, Starbucks sizes
cones
-cluster in and around the fovea (center of eye) -each one transmits to a single bipolar cell that helps relay individual message to the visual cortex -precise information, fine detail -daylight/well-lit -color -low sensitivity in light
Why is somatosensation important?
-communication -decreases stress (oxytocin) -improves health via mindfulness movement
What are some factors that influence perception?
-context (differently sized monsters) -emotion (sad, heavy music vs bouncy, light music) -motivation (water bottle seems closer to those who are thirsty)
How does light reach the retina?
-enters through cornea -passes through pupil -lens focuses light rays into image on light rays
schizophrenia
-high heritability (dopamine overproduction, synapse pruning), environmental triggers -positive (do not normally experience): delusions, sensory hallucinations -negative (absence of normal experience): anhedonia, absence of speech
How are smells processed?
-odor molecules (odorants) bind to receptors -olfactory receptor cells are activated and send electronic signals -the signals are relayed via converges axons -signals are transmitted to higher regions of the brain
the four shared principles of sensation
-physics (physical properties of stimulus) -physiology (body's sensory processing) -phenemenology (person's broader experience) -psychology (perceptions shape ABCs)
miscellaneous
-physiology impacts perception
parallel processing
-processing of many aspects of a problem simultaneously (ex. color, motion, form, depth), processes many functions, integrates separate but parallel work
cornea
-protects eye -bends light to provide focus -how light enters eye
What three steps are basic to all our sensory systems?
-receive sensory stimulation using specialized receptor cells -transform that stimulation into neural impulses -deliver the neural information to your brain
What is the pathway for somatosensation?
-receptors in skin -nerves -primary somatosensory cortex in brain -posterior parietal cortex, where secondary processing takes place -coordinates response -takes info from all senses, processes, sends to motor cortex
monocular depth cues
-relative height: objects higher in our field of vision are farther away -relative motion -relative size -interposition -linear perspective -light and shadow
rods
-share bipolar cells, sending combined messages -detect black, white, gray -peripheral -twilight vision (help see in dark) -highly sensitive to light
iris
-surrounds pupil -controls pupil size -dilates/constricts in response to light intensity and inner emotions
What two physical characteristics of light help determine our sensory experience of them?
-wavelength -intensity
How does light information pass through the retina?
1) light enters eye, triggering reaction in rods and cones in the back of the retina 2) chemical reaction in turn activates bipolar cells 3) bipolar cells activate ganglion cells, the axons of which converge to form the optic nerve. This nerve transmits information to the visual cortex in the brain via the thalamus
Summarize visual information processing
1) retinal processing: receptor rods and cones --> bipolar cells --> ganglion cells 2) feature detection: brain's detector cells respond to specific features (edges, lines, angles) 3) parallel processing: brain cell teams process combined information about color, movement, form, depth 4) recognition: brain interprets constructed image based on information from stored images
How does our system of sensing differ from vision, touch, and taste?
2 types of retinal receptors, 4 basic touch senses, 5 taste sensations, but no basic smell receptors. Instead, different combinations of odor receptors send messages to the brain, enabling us to recognize some 10,000 different smells
Molyneux's problem
Can a cube and sphere be visually distinguished based only on tactile experience? (No) Method: blindness can be corrected; subjects could not distinguish
What are the basic steps in transforming sound waves into perceived sound?
Outer ear collects sound waves, which are translated into mechanical waves by the middle ear and turned into fluid waves in the inner ear. The auditory nerve then translates the energy into electrical waves and sends them to the brain, which receives and interprets the sound.
controlling pain
Pain is a result of biological, psychological, and social-cultural influences. Pain can be addressed with placebos or distractions
Why is taste evolutionary advantageous?
Small children typically resist bitter/sour food because these were potentially dangerous sources of food poisoning. -taste buds regrow every 1-2 weeks, but as you grow older, the number of taste buds/taste sensitivity decreases
What are the two theories of color vision and how do they complement one another?
The Young-Helmholtz trichromatic theory and Hering's opponent process theory outline the stages of color vision: 1) the retina's receptors for red, green, and blue respond to different color stimuli 2) the receptors' signals are then processed by opponent-process cells on their way to the visual cortex in the brain
exteroception
any stimulus from outside
What does research suggest about the effects of experience on perception?
There is a critical period for normal sensory and perceptual development. Although adults are able to distinguish color and brightness (their senses have not degenerated), the cortical cells had not developed normal connections, causing them to be functionally blind to shape. Experience guides the brain's neural organization as it forms the pathways that affect perception.
How do we locate sounds?
Two ears, detects intensity and direction of sound
retinal disparity
a binocular cue for perceiving depth: by comparing images from the retinas in the two eyes (about 2.5 inches apart), the brain computes distance--the greater the disparity between the two images, the closer the object
retina
a multilayered tissue on the eyeball's sensitive inner surface -image appears upside-down and reversed -receptor cells convert light energy into neural impulses, forward those to brain
sensory experience
a prior: beliefs and experiences can influence our perception; role of existing beliefs ex. (Loch ness, UFOs) ex. things that are farther back are smaller: monster picture ex. culture window/box
perceptual set
a set of mental tendencies and assumptions that greatly affects what we perceive -top-down -ex: saxophone man / woman's face picture
pupil
a small adjustable opening in eye
perceptual adaptation
ability to adjust to an artificially displaced or even inverted visual field; humans are able to adapt quickly
depth perception
ability to see objects in three dimensions although the images that strike the retina are two-dimensional -allows us to judge distance
bottom-up processing
analysis that begins with the sensory receptors and works up to the brain's integration of sensory information
How do we normally perceive depth?
binocular and monocular cues
How does wave amplitude affect our perception of colors?
bright colors have great amplitude while dull colors have small amplitude
transduction
process of converting one form of energy into another that your brain can use -how sensory inputs are translated into neural outputs
top-down processing
constructs perceptions from the sensory input by drawing on our experience and expectations
binocular cues
depth cues, such as retinal disparity, that depend on the use of two eyes
olfactory bulb
direct route to amygdala and hippocampus
lens
focuses incoming light rays into an imagine on the retina
sensory context
immediate surrounding environment influences our perception
proprioception
kinetic sense -helps monitor position of body relative to self/in space
Hermann von Helmholtz's place theory (high place)
links the pitch we hear with the place where the cochlea's membrane is stimulated
What kind of wavelengths do red colors have?
long wavelength, low frequency
vestibular sense (body movement)
monitors head's/body's position and movement -movement of fluids in inner ear
sensorineural hearing loss
nerve deafness -damage to cochlea's receptor cells/auditory nerves
grouping
our minds bring order and form by organizing stimuli into groups: 1) proximity (group nearby figures together) 2) continuity (smooth, continuous patterns) 3) closure (fill in gaps to create a complete object
color constancy
perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object -experience of color depends on object's context
perceptual constancy
perceiving objects as unchanging (having consistent shapes, size, brightness, and color) even as illumination and retinal images change
phenomology
perceptions shape ABCs: our perceptions of sensations are not fixed or static, but shaped by sensory experiences, sensory context, sensory experience -Gustave Fechner -humans behave according to naturalistic principles -perceptions are subjective; material world does not exist
volley principle
place theory best explains how we sense high pitches, frequency theory explains how we sense low pitches -combination handles pitches in intermedite range
perception
process by which the brain organizes and interprets sensory input -top-down
accomodation
process in which lens focuses incoming light rays by changing curvature to focus near or far objects on the retina
fovea
retina's area of central focus
kinesthesis (body position)
sense of position and movement of body parts
somatosensation
sense of touch 1) exteroception 2) interoception 3) proprioception
sensation
senses detect information and transmit that info to brain -bottom-up
nociceptors
sensory receptors that detect hurtful temperatures, chemicals, or pressure -respond to stimuli by sending an impulse to spinal cord, which passes the message to the brain, which interprets the signal as pain
What kind of wavelengths do blue colors have?
short wavelength, high frequency
feature detectors
specialized neurons in the occipital lobe's visual cortex that receive information from individual ganglion cells in the retina -nerve cells that respond to specific features of the stimulus, such as shape, angle, movement -responds to a scene's specific features--pass information to other cortical areas, where teams of cells respond to more complex patterns ex. helps recognize faces
priming
the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response
intensity
the amount of energy in light waves (determined by amplitude--height), which influences brightness
Why can odors invoke memories and feelings?
the brain's circuitry for smell connects with taste and areas involved in memory storage -smell is primitive
hue
the color we experience (blue, green, red, etc)
ESP (extrasensory perception)
the controversial claim that perception can occur apart from sensory input
wavelength
the distance from one wave peak to the next
embodied recognition
the influence of bodily sensations, gestures, and other states on cognitive preferences and judgments
difference threshold (just noticeable difference, jnd)
the minimum difference a person can detect between any two stimuli half the time
absolute threshold
the minimum stimulation needed to detect a particular stimulus 50 percent of the time
blind spot
the point at which the optic nerve leaves the eye, creating a "blind" spot because no receptor cells are located there -blind spot is on nose side of retina
sensory interaction
the principle that one sense may influence another -smell of food influences its taste -seeing captions to hear words -brain blends inputs from sensory channels
Weber's law
the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount) ex: two objects must differ in weight by 2 percent -lower levels, easier to notice changes (completely dark; flicker of light is noticeable)
frequency theory (low frequency--wq)
the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch
Young-Helmholtz trichromatic (three-color) theory
the retina has 3 types of color receptors, each especially receptive to red, green, and blue -combinations of these cones through stimuli allows us to see other colors -color-deficient vision lacks red/green sensitive cones
parapsychology
the study of paranormal phenomena, including ESP and psychokinesis
signal detection teory
theory predicting how/when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) -there is no absolute threshold and detection depends partly on a person's experience, expectations, motivation, and alertness
gate-control theory
theory that says the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain. The "gate" is opened by the activity of brain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain
Hering's opponent-process theory
three sets of opponent retinal processes (red-green, yellow-blue, white-black) enable color vision -for example, some cells are stimulated by red and inhibited by green
equilibrioception
vestibular sense: sense of body's position relative to external world (balance, based on fluid in inner ears)
sensory adaptation
when we are constantly exposed to a stimulus that does not change, we become less aware of it because nerve cells fire less frequently -reduces sensitivity, but -allows focus on informative changes without being distracted by background chatter